Hand tool for screwing and unscrewing a screw means

ABSTRACT

A hand tool for tightening or loosening screw elements such as bolts consists of an elbow pipe (24) in which a displaceable and rotatable flexible shaft (26) is mounted. A handle (30) is attached to the rear end of the shaft in order to rotate and displace the shaft inside the elbow pipe (24). A holder (40) with a hexagonal socket for receiving bits is arranged at the front end of the shaft. When the handle is moved to its rearmost position, locking elements cooperate to prevent the holder from rotating in relation to the pipe. When the handle is moved to its forward position these locking elements are disengaged so that the holder and gripping elements can be rotated with the handle.

The present invention relates to a hand tool for screwing and unscrewinga screw means. Such a tool is known by SE 467 532 and is shown in theattached FIGS. 1-4.

In this known tool, a flexible shaft is rotatable and displaceable in anangled tube. A handle is fixed to the rear end of the shaft to operatethe same. To the front end of the shaft, there is fixed an engagingmeans with a hexagonal cross section. To the front end of the tube,there is fixed a holder with a hexagonal socket for receiving theengaging means in non-rotational relation. When the engaging means is tobe rotated with the aid of the handle, the engaging means is pressed outto a free position outside the holder and at the same time a portion ofthe shaft will be exposed outside the holder. If the engaging means issubjected to lateral forces, these will be taken up at the fixing pointbetween the shaft end and the engaging means with the risk of fractureat the point of attachment. If the engaging means is also extended withanother engaging means, the lateral forces will have a longer leverwhich will increase the risk of fracture at the point of attachment. Thepurpose of the invention is to eliminate this disadvantage and makepossible detachable mounting of various types of engaging means withoutthe risk of fracture at any point of attachment.

This is achieved by a hand tool in which, as an engaging means, there isused an interchangeable tip or bit, the front portion of which is aregular screwdriver tip, a cross-head screwdriver tip, a hexagonal pin,a hexagon nut socket or other tool, the rear portion of which ishexagonal in cross-section and is removably insertable into a holder toa non-rotatable position therein. The invention is characterized in thatthe holder has a socket portion which in all positions is guidedrelative to a corresponding portion of the front end portion of thetube. The engaging means can be held in the holder by a magnet, with asnap coupling or by other known means. The holder has a cylindricalbearing surface which cooperates with a corresponding bearing surface onthe front end of the tube and which has such a length that the lateralforces can be absorbed without any risk of fracture at any point ofattachment.

In the accompanying drawings, the known tool is shown in FIGS. 1-4.FIGS. 5-10 show different embodiments of a tool with a holder accordingto the invention for interchangeable holding of an engaging means.

FIG. 1 is a longitudinal section through the known tool with the handlein its forward end position and the engaging means in its advanced endposition free of the end of the tube.

FIG. 2 is the same longitudinal section as in FIG. 1, but with thehandle in its rear end position and the engaging means in its retractireposition in the holder fixed to the end of the tube.

FIG. 3 is a cross section along the line 3--3 in FIG. 1 through theengaging means in the form of a hex-head pin.

FIG. 4 is a cross section along the line 4--4 in FIG. 1 through thehexagonal socket for receiving the hex-head pin.

FIGS. 5-10 show different variants of a holder according to theinvention for interchangeable engaging means with the end in the form ofa screwdriver, a cross-head screwdriver or other tips, which areavailable on the market in sets of tips. The holder, in its variousembodiments in FIGS. 5-8, is locked against rotation relative to thetool by means of cooperating cogs or teeth when the rotating shaft is inits retractire position, and is released for rotation relative to thetube when the rotational shaft is in its extended position in the tube,where the cooperating cogs or teeth are out of engagement.

The numeral 10 designates an angle tube with two main components 12 and14, which form approximately a right angle with each other.

The longer straight tube portion 14 has mounted thereon a rotatable andlongitudinal displaceable handle 16, which, in its forward end positionaccording to FIG. 1 is in contact with the end of the tube 14.

To the handle 16 there is fixed a flexible rotational shaft 18, such asa cable of known design. The shaft extends rotatably through the tube 10and out from the end of the tube portion 12 to the position shown inFIG. 1. To this end of the shaft, there is fixed a hexagonal pin 20which is intended to fit into a corresponding hex-head socket in a bolthead or the like (not shown).

The end of the tube portion 12 is extended with a nut socket weldedthereto, forming a hexagonal socket 22 for receiving the hexagonal pin20 in the manner shown in FIG. 2.

In the position shown in FIG. 1, the pin 20 can be easily rotated byrotating the handle 16. This is particularly advantageous in confinedspaces. After the bolt has been screwed to the bottom and is to betightened, this can be done quite simply. The handle 16 is pulled backto its rear end position shown in FIG. 2, and the shaft follows it andpulls in the pin 20 into a non-rotating position in the socket 22. Thetool will now function as a fixed wrench with a handle which provides arelatively long lever to produce high torque for the final tightening ofthe bolt or the like, or for initial unscrewing of the bolt.

In FIGS. 5, 7 and 9, the numeral 24 designates the angle tube, in whichthe flexible shaft 26 is rotatable and longitudinally displaceable. Atthe rear end of the shaft, there is fixed an end piece with a hexagonalpin 28 for receiving a handle 30. The rear end of the shaft is biased bya compression spring 32, which pushes the shaft towards its rear endposition, where the shaft is locked against rotation relative to thetube by one of the methods described below. Pressing the handle 30against the force of the spring 32 will displace the shaft 26 to itsforward position for free rotation of the shaft 26.

FIGS. 5, 7 and 9 show an engaging means, in this case in the form of ascrewdriver tip or bit 34, the end of which can be a regularscrewdriver, a cross-head screwdriver or other rotating means. The rearportion 38 has a known hexagon section and is non-rotatably inserted ina hexagon socket in a holder, generally designated 40 in FIG. 5, 42 inFIG. 7, and 44 in FIG. 9.

In FIGS. 5 and 6, the rear end of the holder 40 is socket-shaped and isrotatably mounted on the forward end of the tube 24, held securelythereon axially with an annular locking means 46.

A disc 47 is fixed to the front end of the shaft 26. The disc has axialcogs or teeth 47a and is axially displaceable in a cavity in the holder.The axial cogs or teeth 48 on the walls of the cavity are engaged, bydisplacement of the disc, with the teeth of the disc to prevent rotationof the disc relative to the holder. Displacement of the disc in theopposite direction releases the teeth from each other.

FIG. 6 shows the teeth 47a and 48 in an end view. In the position shownin FIG. 5, the tube 24 can be held stationary, and the holder 42 withthe engaging means 34 in place in the screw, can be rotated by means ofthe handle 30. When the handle is released, the spring 32 forces theshaft 26 back to its retracted position and the teeth 47a,48 will engagewith each other, thus locking the holder 40 to the tube 24. The longportion of the tube can then be used as a lever for turning the holder40 with the engaging means. A particular advantage of this device isthat the holder 40 has a constant axial position in the tube 24 and isin contact with its end against an abutment on the outside of the tube,which means that if one applies pressure to the tube 24 to produce abetter engagement between the engaging means and the screw, this can beeasily done by applying pressure to the tool and rotating the longsection at the same time. As can be seen in FIG. 5, the holder is alwaysmounted in place and absorbs any lateral forces on the engaging means,so that they are not transferred to the point of attachment between thedisc 47 and the end of the shaft 26.

FIGS. 7 and 8 show an alternative where the holder 42 is displaceableand rotatable within the end portion 24A of the tube. The holder issecurely joined to the end 26A of the shaft. The holder is shown in FIG.7 in its advanced and rotatable end position. At the rear end portion ofthe holder there are a number of axial teeth 52 lying axially free fromcorresponding axial teeth 54 on the inside of the tube end, in theposition shown in FIG. 7 for rotating the holder. When the pressure onthe handle is released, the spring 32 (FIG. 5) will push the shaft 26back so that the teeth 52,54 will engage with each other and lock theholder to the tube.

The holder is in this case as well securely mounted and can absorblateral forces without they being transferred to the point of attachmentbetween the holder and the end of the shaft.

In FIGS. 9 and 10, the holder 44 is rotatable and is displaceable withinthe tube end 24B. The holder is solidly joined to the shaft 26. The rearend of the holder is provided with radial teeth 54, and correspondingradial teeth 56 are on a washer 58 fixed inside the tube end. When theshaft 26 and the holder are retracted by the spring 32, the teeth 54,56engage and lock the holder against rotation relative to the tube. Whenthe shaft is advanced, the engagement is broken between the teeth 54,56,and the holder with the engaging means can be rotated relative to thetube. An advantage of this locking device is that the displacementmovement between the advanced and retracted end positions can be keptrelatively small in relation to the other embodiments described above.In this case as well, the holder is held securely to absorb lateralforces to prevent fracture between the end of the shaft 26 and theholder.

An additional advantage of the holder shown in FIGS. 5, 7 and 9, is thatthe interacting teeth of the holder and the tube are protected withinthe tube and are prevented from becoming soiled, which could impairengagement of the teeth.

We claim:
 1. In a hand tool for screwing and unscrewing a screw meansthat has a screw head, said tool having means for non-rotatably engaginga said screw head, said tool comprising a handle comprising an angledtube, a flexible shaft extending within said angled tube, means at oneend of said tube for moving said shaft lengthwise of said tube betweenan extended position and a retracted position, said engaging means beinginterconnected with the other end of said flexible shaft such that insaid extended position of said flexible shaft said engaging means andsaid flexible shaft are rotatable relative to said angled tube and insaid retracted position of said flexible shaft said flexible shaft andsaid engaging means are fixed against rotation relative to said angledtube; the improvement wherein said engaging means is supported on and byan end of said angled tube both in said retracted position of saidflexible shaft and in said extended position of said flexible shaft. 2.A tool as claimed in claim 1, wherein said engaging means has apolygonal socket for releasably retaining a tool engageable with a saidscrew head.
 3. A tool as claimed in claim 2, wherein said polygonalsocket is hexagonal.
 4. A tool as claimed in claim 1, wherein saidengaging means is rotatably mounted with an inner cylindrical bearingsurface on a corresponding external cylindrical bearing surface on saidend of the angled tube.
 5. A tool as claimed in claim 1, wherein saidother end of said flexible shaft and said end of said hollow tube havenoncircular portions thereon that are out of engagement with each otherin said extended position of said flexible shaft and are in matingengagement with each other in said retracted position of said flexibleshaft to prevent rotation of said flexible shaft relative to said tube.6. A tool as claimed in claim 1, and means preventing rotation of saidflexible shaft relative to said engaging means but permitting lengthwisemovement of said flexible shaft between said extended and retractedpositions relative to said engaging means.
 7. A tool as claimed in claim6, and means preventing movement of said engaging means lengthwise ofand relative to said tube but permitting rotation of said engaging meansrelative to said tube.
 8. A tool as claimed in claim 1, and spring meanscontinuously urging said flexible shaft toward said retracted position.9. A tool as claimed in claim 1, said engaging means extending withinsaid end of said angled tube both in said retracted and in said extendedposition of said flexible shaft.